JADE, or JAHDE  , a deep bay and estuary of the North Sea, belonging to the grand-duchy of Oldenburg, Germany . The bay, which was for the most part made by storm-floods in the 13th and 16th centuries, measures 70 sq. m., and has communication with the open sea by a fairway, a mile and a half wide, which never freezes, and with the tide gives access to the largest vessels . On the west side of the entrance to the bay is the Prussian naval port of Wilhelmshaven . A tiny stream, about 14 M. long, also known as the Jade, enters the head of the bay .